The present invention is directed to plastic boards having extremely high metal content circuit patterns formed thereon. The circuit boards are useful for mounting and interconnecting electrical components thereto.
In the past extremely high metal content circuit patterns in particulate form were laid down on ceramic boards and then heated to form a fused circuit (see U.S. Pat. Nos. 3,729,819, 3,950,200 and 3,576,668). Less expensive boards of plastic materials could not be used in this process since the plastic boards will not withstand the high processing temperatures needed for the fusing of the metal.
While it is possible to form circuits on plastic boards using conventional methods, e.g. spraying, screening and the like, these methods are not as practical as one would like for use in high volume manufacturing operations when using highly loaded metal particulate slurries to form the pathways. Accordingly, a new and improved method and materials were needed to be able to produce high metal content circuit patterns (electrically conductive pathways) on circuit boards. This invention provides additional advantages over current processes in that circuit patterns on release layers (peel-off layers) may be mass produced for customers who can then laminate and transfer such circuit patterns to substrates.